There are many applications in which electrical power lines as well as auxiliary electrical lines are established by means of multi-connector cord from one fixed location to another. In many applications it is undesirable to establish a semi-permanent connection as by soldering or using screws and terminal blocks. This is particularly true, for example, in the case of machines or instruments used in a production line. If a production line machine malfunctions or requires periodic maintenance, it is more desirable to use a plug and receptacle capable of being disconnected quickly to remove the defective machine and to replace it with an operative one by quickly coupling the plug and connector together again.
In many assembly line applications, the machine has a prong or blade-type male connector mounted to a vertical surface so that the connecting elements extend along a horizontal line. It is also commonplace to have such installations requiring connectors having two, three, four or even more poles. For example, in the case of a machine being connected by means of a cord to a controller, two wires may be used to connect a source of electrical power to the machine; one or more additional wires may be used to establish a control function from the controller to the machine; and one or more additional may be used to establish a sensing function at the machine. In such cases, it is necessary that provision be made so that the proper connecting elements are coupled to their corresponding connecting elements. Thus, an interfitting mechanical structure such as a key and key way may provide proper alignment, or alignment may be accomplished through an unique or asymmetrical configuration of the male/female connecting elements of the connector.
It is thus common that an electrical cord being connected to a fixed connector at a machine may have to be twisted on its own axis so that the connecting elements are properly aligned before the cord is assembled to the connector on the machine. Usually, a threaded nut will provide mechanical coupling to maintain the connection; however, the twisted cord may extend laterally outwardly from the machine in the form a gooseneqk and form an obstruction or unsightly, if not unsafe, arrangement. Any bumping of the cord will increase the stress on internal connection, already present due to the twisting of the cord. Thus, in some cases it may be difficult to locate properly or "dress" the cord relative to the machine plug so that the cord is out of the way and not likely to interfere with nearby work going on or to be inadvertently pulled or dislodged by a passing worker or other machine being moved.
As mentioned, a twisted cord hanging from a machine at a 90.degree. angle, for example, may induce an undesirable bending moment between the wire and the connecting elements in the cord, thereby stressing that connection. In other words, if the connector at the end of a cord is requried to make a connection along a horizontal axis, as distinguished from a vertical axis along which the cord simply hangs, there is obviously an undesirable stress on the connector at the end of the cord and on the coupling itself, leaving the connector vulnerable to damage by passing machines or people or to fatigue through bending of the connector elements.